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From: "kretz at kde dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/49133] [4.6/4.7 Regression] modification of aliased __m128d miscompiles
Date: Tue, 24 May 2011 10:36:00 -0000	[thread overview]
Message-ID: <bug-49133-4-GGv4OEhCgt@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-49133-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49133

--- Comment #2 from Matthias Kretz <kretz at kde dot org> 2011-05-24 10:16:41 UTC ---
I applied the patch to the latest 4.6 snapshot. I confirm that it fixes the
bug. Also, there are no regressions in my testsuite.

Just for confirmation, the patched sse.md looks like this for me now (starting
from line 4952):
(define_insn "sse2_loadhpd"
  [(set (match_operand:V2DF 0 "nonimmediate_operand"     "=x,x,x,o,o,o")
    (vec_concat:V2DF
      (vec_select:DF
        (match_operand:V2DF 1 "nonimmediate_operand" " 0,0,x,0,0,0")
        (parallel [(const_int 0)]))
      (match_operand:DF 2 "nonimmediate_operand"     " m,x,0,x,*f,r")))]
  "TARGET_SSE2 && !(MEM_P (operands[1]) && MEM_P (operands[2]))"
  "@
   movhpd\t{%2, %0|%0, %2}
   unpcklpd\t{%2, %0|%0, %2}
   shufpd\t{$0, %1, %0|%0, %1, 0}
   #

Question, why not use unpcklpd instead of shufpd $0? On older CPUs unpcklpd
should be slightly faster than shufpd.


  parent reply	other threads:[~2011-05-24 10:33 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-23 22:20 [Bug target/49133] New: [4.6 " kretz at kde dot org
2011-05-24  8:54 ` [Bug target/49133] [4.6/4.7 " ubizjak at gmail dot com
2011-05-24 10:36 ` kretz at kde dot org [this message]
2011-05-24 11:48 ` ubizjak at gmail dot com
2011-05-24 11:54 ` ubizjak at gmail dot com
2011-05-24 15:58 ` uros at gcc dot gnu.org
2011-05-24 18:58 ` uros at gcc dot gnu.org
2011-05-25  8:15 ` jakub at gcc dot gnu.org
2011-05-25 13:47 ` uros at gcc dot gnu.org
2011-05-25 16:43 ` uros at gcc dot gnu.org

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